Rational choice theory commonly assumes that the presence of unselected choices cannot impact which among the remaining choices is selected—-often referred to as “independence of irrelevant alternatives.” We show that such seemingly irrelevant alternatives influence choice in a school lunch setting. In these lunchrooms, we provide evidence that the presence of specific side dishes-—trigger foods-—can strongly increase the sales of unhealthy à la carte options, even when the trigger foods are not selected. This behavioral anomaly can be exploited to lead children to healthier choices. We also offer a method that can be used to identify such foods.